1. Field of the Invention
This invention relates generally to solar heating systems, and more particularly to solar heating systems that utilize air as a heat transfer medium.
2. Description of the Prior Art
Most solar heat collections systems utilize the infrared radiation of the sun to raise the temperature of a working fluid. Water and air are by far the two most common working fluids for solar heating systems.
A solar heat collection panel is the part of a solar heating system which actually absorbs the solar radiation and typically includes a frame covered with a piece of glass or other transparent material. Solar radiation is transmitted through the glass and impinges heat absorptive surfaces to raise the temperature of those surfaces. The working fluid flows past these heat absorptive surfaces to cause a transfer of heat. The fluid is then put to a useful purpose, such as to heat a home or hot water supply.
The working fluid can be caused to flow past the heat absorptive surfaces by mechanical means such as a pump or fan, or can be caused to flow past the heat absorptive surfaces by intrinsic thermodynamic forces. For example, one type of solar heat collection panel utilizes the convective properties of the heated air to draw cool air across the heat absorptive surfaces. The heated air can then be mixed with the air within an enclosure.
Solar heating systems are particularly attractive in situations where energy is either expensive or hard to obtain. One such situation is in the heating of beehives, which should be maintained at a relatively high temperature so that the bees remain productive. During the winter when the outside temperature is low, bees will consume honey to produce body heat to warm up the hive. This, of course, reduces the amount of honey that a beekeeper can sell. It has been found that if the brood nest area of the hive is kept near 94.1.degree. F., the adult fliers will stop consuming the honey and will start to store new honey. Thus, proper heating of a beehive can make it vastly more productive.
In the past, the temperature within a beehive was raised by two basic techniques. A first technique was to feed the bees a yeast and syrup mixture so that they had enough food to both heat the hive and produce honey. The second technique was to artificially heat the hive with an electric heater. Both of these techniques tend to be prohibitively expensive, and often commercially infeasible. It has been calculated that, for a large scale honey operation, syrup and/or electric costs can run into thousands of dollars per month.
Beehives have been provided with solar heating systems in the past. For example, in U.S. Pat. No. 4,300,250 of Taylor a solar heater for beehives is disclosed including a solar collection box provided with a transparent wall through which solar radiation may enter, and a thermally conductive sheet located within the box to transmit heat to the beehive.
A problem with Taylor's solar heating system is that it is a relatively inefficient absorber of solar radiation. The transparent wall and conductive sheet of Taylor's collection box is vertical to the ground and thus will not collect a large portion of the solar radiation incident upon it. It has been well established in the prior art that a solar heating panel is maximally efficient only when it is angled such that, on the average, the incident solar radiation is perpendicular to the panel's surface.
Another problem with with Taylor's system is that it is cumbersomely heavy and large. Furthermore, the size of Taylor's system increases the cost of the system due to the large amount of materials required in its construction.
Solar heating systems are most often used to heat the air within habitable enclosures such as houses, apartments, and business premises. Such systems usually include a large array of solar heat collecting panels coupled to the central heating system and operated by an elaborate control system. These solar heating systems are very expensive to install and maintain.
Solar heating systems in general have a number of problems. For one, solar heating systems tend to be large, cumbersome, and non-portable. Furthermore, solar heating systems are, due to their large g1ass area, especially vulnerable to damage due to vandalism and exposure to the elements. Also, solar heating systems must often be provided with elaborate control systems so that they do not collect heat when it is not wanted, such as during the summer.